It's not often that paleontology makes the news. This week, however, it did - in a big way. And let me tell you, it wasn't the edgy paper on a new assemblage of South American bivalves ("Barremian Bivalves from the Huitrín Formation, West-Central Argentina: Taxonomy and Paleoecology of a Restricted Marine Association") that was all over the rolling news channels.

No; it's the news that Archaeopteryx may be knocked off its pedestal as the earliest bird in the fossil record, based on a new phylogeny by Xu et al.Archaeopteryx is now deemed to be just another deinonychosaur; probably closer to velociraptor than to birds.

And talk about spectacularly bad timing: this news comes just as we were about to celebrate 150 years since Archaeopteryx's discovery.

The thing is, Archeopteryx has been looking increasingly uncomfortable on that pedestal for quite a while. Murmurs of discontent have been flying around since the 1940s. So why is it all of a sudden no longer considered to be a bird?

We'd better start with defining what we really mean by a bird. In fact, what we mean by "bird" is probably the real nub of the issue.

The birds are a group of therapod dinosaurs, and as such are the only group of dinosaurs still to roam the Earth. (Annoy your friends by mentioning this any time they try to tell you dinosaurs are extinct. I like to tell people that a dinosaur has just shat on their car.) The earliest birds split from other maniraptoran dinosaurs at about 150 Ma.

Here's the tricky bit, then: at what point does a maniraptoran dinosaur become a bird? Back in the day, when we had a lot less fossils, it was a lot easier. Birds have feathers and wishbones. Simple. But slowly, we've found more and more examples of what were thought were bird-only characters turning up in theropod dinosaurs - so much so, that what we now think of as unique to birds is very different.

For a start, feathers. Birds have feathers, dinosaurs don't. End of, right?

Well, for a while now, feathers have been turning up on dinosaurs left right and centre. For a start, Velociraptor, (the most overhyped dinosaur ever, being no bigger than a dog), was covered in feathers, and in fact, many basal dromeosaurs are at least thought to have been able to glide. Even young tyrannosauruses may have had some fine downy feathers. So, these days, feathers don't imply bird at all.

The next avian characteristic is the wishbone, or furcula. The furcula, as anyone who has boned a chicken before will know, is simply two fused collarbones, and has always been thought to strengthen the chest of birds to withstand the rigours of flight.

Again, now we've started to find more and more theropods that have furculae. Coelophysoids, spinosauroids, allosauroids, tyrannosauroids, compsognathids, oviraptorosaurs - they've all got them.

But these are just two examples. To name a few more previously bird-only features that are now found across the deinonychosaurs, we have the antorbital fossa being dorsally bordered by the nasal and lacrimal, a relatively small number of caudal vertebrae, a relatively large proximodorsal process of the ischium, a relatively long pre-acetabular process of the ilium, fusion of the proximal part of the metatarsus... among others.

Are there any left? Two things that are still bone fide bird features are a reversed hallux (the big toe; in perching birds, it's reversed; this is how they cling onto branches) and a smooth palatine, both of which have always thought to have been present on Archaeopteryx.

However, it's actually pretty difficult to be able to tell orientations of parts of anatomy on fossils, which are almost always 2D. So, opinion has shifted recently to the hallux not being reversed in Archaeopteryx. This might seem like a bit of an oversight, but I must say, I have seen the London specimen of Archaeopteryx, and, truth be told, I actually found it difficult at a first glance to even see where the head was. The fossil of Archeopteryx has the appearance of having been shot out of a cannon at a wall; there's nothing neat about it. So, whether the hallux points forwards or back is very subjective, and likewise with the jugal process on the palatine bone; we no longer think that Archaeopteryx lacks one.

Essentially, then, it's become difficult to have a phylogeny of theropods with Archaeopteryx being the first bird. Under the new phylogeny, this accolade goes to one of Epidexipteryx, Jeholornis and Sapeornis - relatively new kids on the block, having only been around for 10 years or so.

This reclassification also clears up a few other inconsistencies as well. The triangular, sharp-toothed skull of Archaeopteryx was very much a carnivourous skull, and moving it out of birds and into the carnivorous deinonychosaur group makes sense; it now seems clear that herbivory was ubiquitous among basal birds, rather than carnivory re-evolving in this group.

I will say this, though: don't expect this to be the last you've heard of this. I think it is probably quite likely that there may be another reclassification, and Archeopteryx may find itself being reclassified as a bird again. Nonetheless, we a still entering into an era where Archaeopteryx is just one of many animals on the slow transition to birds.

For now, though, I think we should all pay our respects to that icon of evolution that is Archaeopteryx. It is still the original, epitome example of a transitional fossil, and is undoubtedly still the most historically important fossil ever found. Though it has been rather lonely, perched there between theropods and birds, there are now many, many more fossils to keep it company. One thing's for sure, though, and that's that the line between what is a dinosaur and what is a bird is more blurred than ever.

It depends on what you want. If you want perfect grammar, USA Today has that - and their journalists know nothing about science and write 400 word articles for 8th graders. If you want good science from experts instead, don't be petty.

It depends on what you define as petty. Expecting sentences to make sense without being thrown off by rogue apostrophes is not. Corrections when they are valid is not. You think USA Today has perfect grammar? Think again.

I'm no Jean Piaget but I thought reading comprehension was taught in grade school - however, if you were truly confused by "its" and "it's" and got nothing from the article due to that, please accept my apologies for calling you petty.

Interesting that in a science forum, Hank thinks that sarcasm actually proves anything. It has nothing to do with comprehension or confusion, and no one said that. Perhaps learn a bit of rational thinking, and avoid simple straw-man arguments.

Good summary of the situation. It really does come down to semantics, and what you call a "bird."

(P.S. Always nice to click an article on a random Google News article and see somebody featuring my artwork. Please note though, as stated at the original upload location http://commons.wikimedia.org/wiki/File:Velociraptor_dinoguy2.jpg this particular piece is free to use under a Creative Commons Attribution license, which as the name implies requires attribution.)

What I like the most of this argument is the fact that this is an epitome of a transitional fossil. It seems as if it is right in the middle of both early bird and late dinosaur. Since science is falsifiable and in that lies the beauty of science. Take that creationist! lol

I've fixed the offending apostrophe. I rather rushed this one out without proof reading it before I left work today, so a couple of errors slipped through the net - sorry about that! It's nice to know that some people care about correct grammar...

I don't see what all the fuss is about. Archaeopteryx was the first discovery of its kind, and its discovery led paleontologists to examine other fossils for feathers. This is how science works: slowly building on the discoveries of the past. Xu and his associates are fortunate to have primary access to the greatest trove of feathered fossils ever found, and his work has increased our knowledge in the field. But the fact that birds evolved from relatives of feathered dinosaurs is still pretty much undisputed. Nothing has changed except that more examples of Archaeopteryx-like fossils have been found to support the hypothesis.

To me, the author has slanted the article to make the simple expansion of paleontological knowledge look like a revolution of some kind. Sadly, he's played into the hands of Creationist types who will use his article to "prove" that the science isn't reliable, which is hardly what he intended when he wrote it.

Fair enough, but you still can't deny that Archaeopteryx is an iconic fossil that many - including myself - care about deeply because of its crucial historic role, and so I think that where it fits in the grand scheme of things is pretty important, actually.

From my dealings with creationists, they will grab at anything to try and show that "science is broken", and sadly this will be no exception. But it's obvious to everybody else that all that's really happened is that there are so many more transitional fossils than there has ever been, and Archaeopteryx is now a member of a rich continuum of animals. It's just not necessarily at the base any more.

Speaking as a linguist, I must inform proofreader, who seems to have once read a style manual, that the apostrophe plays no part whatsoever in the grammar of the English language. The use of the apostrophe, whether to indicate the possessive case or to indicate an omission of letters, is a matter of orthography. The convention that the apostrophe should not be used to indicate 'of it' is unknown to many users of English, and they seem not to have broken out in suppurating pustules from a surfeit of "it'ses". The last term is, of course, the correct plural of "it's".

One might mention, in passing, that the apostrophe should not be confused with the 'okina, nor the latter with the ocarina despite the similarity of shape. On close inspection with any convenient hand-held monocular device for the enhancement of vision, one may see clearly that the 'okina has no holes. Which stands in stark contrast to the apostrophical ratiocination of our commenter proofreader.

The rules of orthography permit indefinite concatenation of apostrophe-esses. Thus, having once more written "it'ses", I may refer to the two locations in this text typographically as the two it'ses's locations, and, verbally, as the two it'ses's locations.

But before our critic seizes upon my 'incorrect' use of the term 'verbal', I must defer to the original use of that term, before the rise of the knuckle-rapping pedagogic grammarians, to indicate 'words generally'.

Hank: great cartoon!

Oliver: an excellent and most thought-provoking article. It seems that archaeopteryx is now, to paleontologists, what Pluto is to astronomers: a source of much argument about the niceties of classification schemes.

Oh, yes, I nearly forgot.

"No; it's the news that Archaeopteryx may be knocked off it's pedestal as the..."

The semicolon is hopelessly wrong: the colon is much more appropriate.I guess they don't teach you punctuation in Ph.D. school.

Farewell, Archaeopteryx or farewell Oliver? Please bring back the 'Friday Fossil' or should it be 'Friday's Fossil'? Anyway, I think your punctuation and its content, or is it 'it's content' is wonderful but then I've never really understood apostrophes, who does other than Patrick?

I've been so busy with work that I haven't found the time to write, and unfortunately I'm going to be in Canada on fieldwork for the next 3 weeks, so no more articles for a bit! But after that, don't worry, I'll be back.

First, as a professional journalist for three decades and an editor for the last 11 years, I want to thank Lockerby for his delicious takedown of a nit-picker. Yes, it was incorrect usage. People make mistakes. But did it in any way decrease your ability to understand what the author was saying? If so, please extract the broomstick from your orifice.

As for Archeopteryx, earlier this year we had the chance to spend a lot of time up close with the Thermopolis Archeopteryx, a truly amazing fossil. Yep, it's somewhere between a dino and a bird - and people are going to debate where, exactly, for a long, long time.

The more interesting question is: Is it reaally transitional - or just a dead end? The only ones found all come from the same area, and there are no clear examples of anything that could be a later species.